Uraemic patients demonstrate cognitive deficits, particularly in attention and memory and chronic kidney disease (CKD) is a risk factor for cognitive impairment. Memory enhancing properties of angiotensin-converting enzyme inhibitors (ACEI) and angiotensin receptor antagonists (AlIA) have been reported in rats and mice. In humans, chronic treatment with an AlIA improved cognition in elderly hypertensive patients; ACEls improve cognition in young, hypertensive patients and acute administration of an AlIA has cognition-enhancing effects in young, healthy volunteers. The aim of this thesis was to investigate possible differential effects of ACEI and AlIA on mood and cognition in comparison to other antihypertensives in CKD patients. To rule out the possible effect of chronic disease on mood and cognition by examining neurocognitive attributes of colon cancer patients in remission, and finally to investigate the possible contribution of renin angiotensin system (RAS) gene polymorphisms to neurocognitive improvement associated with drugs targeted at the RAS.